Problem:
 a(x1) -> x1
 a(a(b(x1))) -> c(c(c(x1)))
 c(x1) -> b(a(x1))
 c(b(x1)) -> x1

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    b1(5) -> 6*
    a1(4) -> 5*
    a0(1) -> 2*
    b0(1) -> 1*
    c0(1) -> 3*
    1 -> 3,4,2
    4 -> 5*
    6 -> 3*
  problem:
   
  Qed